PROKARYOTES Chapter 16 Microbial Life: Prokaryotes and Protists 1

PROKARYOTES Chapter 16 Microbial Life: Prokaryotes and Protists 1
PROKARYOTES © 2012 Pearson Education, Inc. 1

16.1 Prokaryotes are diverse and widespread
Prokaryotic cells are smaller than eukaryotic cells. Prokaryotes range from 1–5 µm in diameter. Eukaryotes range from 10–100 µm in diameter. The collective biomass of prokaryotes is at least 10 times that of all eukaryotes. © 2012 Pearson Education, Inc. 2

Figure 16.1 Bacteria on a pin point
Figure 16.1 Bacteria on the point of a pin 3

Prokaryotes live in habitats too cold, too hot, too salty, too acidic, and too alkaline for eukaryotes to survive. Some bacteria are pathogens, causing disease. But most bacteria on our bodies are benign or beneficial. © 2012 Pearson Education, Inc. 4

Several hundred species of bacteria live in and on our bodies, decomposing dead skin cells, supplying essential vitamins, and guarding against pathogenic organisms. Prokaryotes in soil decompose dead organisms, sustaining chemical cycles. © 2012 Pearson Education, Inc. 5

16.2 External features contribute to the success of prokaryotes
Prokaryotic cells have three common cell shapes. Cocci are spherical prokaryotic cells. They sometimes occur in chains that are called streptococci. Bacilli are rod-shaped prokaryotes. Bacilli may also be threadlike, or filamentous. Spiral prokaryotes are like a corkscrew. Short and rigid prokaryotes are called spirilla. Longer, more flexible cells are called spirochetes. © 2012 Pearson Education, Inc. 6

Figure 16.2A Figure 16.2A Prokaryote shapes Cocci Bacilli Spirochete 7

Nearly all prokaryotes have a cell wall. Cell walls provide physical protection and prevent the cell from bursting in a hypotonic environment. When stained with Gram stain, cell walls of bacteria are either Gram-positive, with simpler cell walls containing peptidoglycan, or Gram-negative, with less peptidoglycan, and more complex and more likely to cause disease. © 2012 Pearson Education, Inc. 8

Figure 16.2B Gram-positive (purple) and gram-negative (pink) bacteria
9

The cell wall of many prokaryotes is covered by a capsule, a sticky layer of polysaccharides or protein. The capsule enables prokaryotes to adhere to their substrate or to other individuals in a colony and shields pathogenic prokaryotes from attacks by a host’s immune system. © 2012 Pearson Education, Inc. 10

Figure 16.2C Tonsil cell Capsule Figure 16.2C Capsule Bacterium 11

Some prokaryotes have external structures that extend beyond the cell wall. Flagella help prokaryotes move in their environment. Hairlike projections called fimbriae enable prokaryotes to stick to their substrate or each other. © 2012 Pearson Education, Inc. 12

Figure 16.2D Flagella Figure 16.2D Flagella and fimbriae Fimbriae 13

16.3 Populations of prokaryotes can adapt rapidly to changes in the environment
Prokaryote population growth occurs by binary fission, can rapidly produce a new generation within hours, and can generate a great deal of genetic variation by spontaneous mutations, increasing the likelihood that some members of the population will survive changes in the environment. © 2012 Pearson Education, Inc. 14

The genome of a prokaryote typically has about one-thousandth as much DNA as a eukaryotic genome and is one long, circular chromosome packed into a distinct region of the cell. Many prokaryotes also have additional small, circular DNA molecules called plasmids, which replicate independently of the chromosome. © 2012 Pearson Education, Inc. 15

Chromosome Plasmids Figure 16.3A
Figure 16.3A DNA released from a ruptured bacterial cell 16

Bacterium Endospores Figure 16.3b
Figure 16.3B An endospore within an anthrax bacterium cell Endospores 18

16.4 Prokaryotes have unparalleled nutritional diversity
Prokaryotes exhibit much more nutritional diversity than eukaryotes. Two sources of energy are used. Phototrophs capture energy from sunlight. Chemotrophs harness the energy stored in chemicals. © 2012 Pearson Education, Inc. 19

Two sources of carbon are used by prokaryotes. Autotrophs obtain carbon atoms from carbon dioxide. Heterotrophs obtain their carbon atoms from the organic compounds present in other organisms. © 2012 Pearson Education, Inc. 20

The terms that describe how prokaryotes obtain energy and carbon are combined to describe their modes of nutrition. Photoautotrophs obtain energy from sunlight and use carbon dioxide for carbon. Photoheterotrophs obtain energy from sunlight but get their carbon atoms from organic molecules. Chemoautotrophs harvest energy from inorganic chemicals and use carbon dioxide for carbon. Chemoheterotrophs acquire energy and carbon from organic molecules. © 2012 Pearson Education, Inc. 21

Energy source Carbon source Sunlight Chemicals Photoautotrophs
Figure Energy source Sunlight Chemicals Photoautotrophs Chemoautotrophs CO2 Oscillatoria Unidentified “rock-eating” bacteria Photoheterotrophs Carbon source Chemoheterotrophs Figure 16.4 Sources of energy and carbon in prokaryotic modes of nutrition Organic compounds Salmonella typhimurium Rhodopseudomonas 22

16.6 CONNECTION: Prokaryotes help clean up the environment
Prokaryotes are useful for cleaning up contaminants in the environment because prokaryotes have great nutritional diversity, are quickly adaptable, and can form biofilms. © 2012 Pearson Education, Inc. 23

Prokaryotic decomposers are the mainstays of sewage treatment facilities. Raw sewage is first passed through a series of screens and shredders. Solid matter then settles out from the liquid waste, forming sludge. Sludge is gradually added to a culture of anaerobic prokaryotes, including bacteria and archaea. The microbes decompose the organic matter into material that can be placed in a landfill or used as fertilizer. © 2012 Pearson Education, Inc. 25

Liquid wastes are treated separately from the sludge. Liquid wastes are sprayed onto a thick bed of rocks. Biofilms of aerobic bacteria and fungi growing on the rocks remove much of the dissolved organic material. Fluid draining from the rocks is sterilized and then released, usually into a river or ocean. © 2012 Pearson Education, Inc. 26

Rotating spray arm Rock bed coated with aerobic prokaryotes and fungi
Figure 16.6A Rotating spray arm Figure 16.6A The trickling filter system at a sewage treatment plant Rock bed coated with aerobic prokaryotes and fungi Liquid wastes Outflow 27

Bioremediation is becoming an important tool for cleaning up toxic chemicals released into the soil and water by industrial processes. Environmental engineers change the natural environment to accelerate the activity of naturally occurring prokaryotes capable of metabolizing pollutants. © 2012 Pearson Education, Inc. 28

Figure 16.6b Figure 16.6B Treatment of an oil spill in Alaska 29

16.7 Bacteria and archaea are the two main branches of prokaryotic evolution
New studies of representative genomes of prokaryotes and eukaryotes strongly support the three-domain view of life. Prokaryotes are now classified into two domains: Bacteria and Archaea. Archaea have at least as much in common with eukaryotes as they do with bacteria. © 2012 Pearson Education, Inc. 30

Table 16.7 Table 16.7 Differences between the domains Bacteria, Archaea, and Eukarya 31

16.8 Archaea thrive in extreme environments—and in other habitats
Archaeal inhabitants of extreme environments have unusual proteins and other molecular adaptations that enable them to metabolize and reproduce effectively. Extreme halophiles thrive in very salty places. Extreme thermophiles thrive in very hot water, such as geysers, and acid pools. © 2012 Pearson Education, Inc. 32

Figure 16.8A Orange and yellow colonies of heat-loving archaea growing in a Nevada geyser
33

16.8 Archaea thrive in extreme environments—and in other habitats
Methanogens live in anaerobic environments, give off methane as a waste product from the digestive tracts of cattle and deer and decomposing materials in landfills. © 2012 Pearson Education, Inc. 34

16.9 Bacteria include a diverse assemblage of prokaryotes
The domain Bacteria is currently divided into five groups, based on comparisons of genetic sequences. 1. Proteobacteria are all gram negative, share a particular rRNA sequence, and represent all four modes of nutrition. © 2012 Pearson Education, Inc. 35

Proteobacteria also include Rhizobium species that live symbiotically in root nodules of legumes and convert atmospheric nitrogen gas into a form usable by their legume host. Symbiosis is a close association between organisms of two or more species. Rhizobium is an endosymbiont, living within another species. © 2012 Pearson Education, Inc. 36

Figure 32.13B Root nodules on a soybean plant
Shoot Bacteria within vesicle in an infected cell Nodules Roots Figure 32.13B Root nodules on a soybean plant 37

2. Gram-positive bacteria rival proteobacteria in diversity and include the actinomycetes common in soil. Streptomyces is often cultured by pharmaceutical companies as a source of many antibiotics. © 2012 Pearson Education, Inc. 38

Figure 16.9B Streptomyces, the source of many antibiotics
39

3. Cyanobacteria Cyanobacteria are the only group of prokaryotes with plantlike, oxygen-generating photosynthesis. Some species, such as Anabaena, have specialized cells that fix nitrogen. © 2012 Pearson Education, Inc. 40

Nitrogen-fixing cells
Figure 16.9c Photosynthetic cells Capsule Nitrogen-fixing cells Figure 16.9C Anabaena, a filamentous cyanobacterium 41

4. Chlamydias Chlamydias live inside eukaryotic host cells. Chlamydia trachomatis is a common cause of blindness in developing countries and is the most common sexually transmitted disease in the United States infecting urethral cells. © 2012 Pearson Education, Inc. 42

Figure 16.9D Chlamydia cells (arrows) inside an animal cell
43

Figure 16.9E Treponema pallidum, the spirochete that causes syphilis
45

16.10 CONNECTION: Some bacteria cause disease
All organisms are almost constantly exposed to pathogenic bacteria. Most bacteria that cause illness do so by producing a poison or toxins. © 2012 Pearson Education, Inc. 46

16.11 Koch’s postulates are used to prove that a bacterium causes a disease
Koch’s postulates are four essential conditions used to establish that a certain bacterium is the cause of a disease. They are 1. find the bacterium in every case of the disease, 2. isolate the bacterium from a person who has the disease and grow it in pure culture, 3. show that the cultured bacterium causes the disease when transferred to a healthy subject, and 4. isolate the bacterium from the experimentally infected subject. © 2012 Pearson Education, Inc. 47

16.11 SCIENTIFIC DISCOVERY: Koch’s postulates are used to prove that a bacterium causes a disease
Koch’s postulates were used to demonstrate that the bacterium Helicobacter pylori is the cause of most peptic ulcers. The 2005 Nobel Prize in Medicine was awarded to Barry Marshall and Robin Warren for this discovery. © 2012 Pearson Education, Inc. 48

16.12 Protists are an extremely diverse assortment of eukaryotes
Protists are a diverse collection of mostly unicellular eukaryotes, may constitute multiple kingdoms within the Eukarya, and refer to eukaryotes that are not plants, animals, or fungi. © 2012 Pearson Education, Inc. 50

Protists obtain their nutrition in many ways. Protists include autotrophs, called algae, producing their food by photosynthesis, heterotrophs, called protozoans, eating bacteria and other protists, heterotrophs, called parasites, deriving their nutrition from a living host, and mixotrophs, using photosynthesis and heterotrophy. © 2012 Pearson Education, Inc. 51

Autotrophy Heterotrophy Mixotrophy Caulerpa, a green alga
Figure 16.12A Autotrophy Heterotrophy Mixotrophy Figure 16.12A Protist modes of nutrition Caulerpa, a green alga Giardia, a parasite Euglena 52

Figure 16.12B A protist (excavate) from a termite gut covered by thousands of flagella
Figure 16.12B A protist from a termite gut covered by thousands of flagella, viewed with scanning electron microscope (left) and light microscope (below). 54

16.13 Endosymbiosis of unicellular algae is the key to much protist diversity
Recent molecular and cellular studies indicate that nutritional modes used to categorize protists do not reflect natural groups and that endosymbiosis has occurred. Protist phylogeny remains unclear. One hypothesis, used here, proposes four monophyletic supergroups. © 2012 Pearson Education, Inc. 55

16.14 The SAR supergroup represents the range of protist diversity
Stramenopiles include diatoms, unicellular algae with a glass cell wall containing silica, brown algae, large complex algae with characteristic brown pigments in their chloroplasts like seaweed and kelp water molds, unicellular heterotrophs that are usually freshwater decomposers © 2012 Pearson Education, Inc. 56

Figure 16.14A Diatom, a unicellular alga that is a stramenopile
57

16.17 Rhizarians include a variety of amoebas
Foraminiferans are found in the oceans and in fresh water, have porous shells, called tests, composed of calcium carbonate, and have pseudopodia that function in feeding and locomotion. © 2012 Pearson Education, Inc. 58

Figure 16.14B Brown algae: a kelp “forest”, a stamenopile
59

Figure 16.14C Water mold, a stramenopile
Figure 16.14C Water mold (white threads) decomposing a goldfish 60

Figure 16.14D A red tide caused by Gymnodinium, a dinoflagellate
62

Alveolata include dinoflagellates, unicellular autotrophs, heterotrophs, and mixotrophs that are common components of marine plankton, ciliates, unicellular heterotrophs and mixotrophs that use cilia to move and feed, a group including parasites, such as Plasmodium, which causes malaria. © 2012 Pearson Education, Inc. 63

Figure 16.14E A freshwater ciliate showing cilia distributed over the cell surface and around the mouth Mouth Cell mouth Figure 16.14E A freshwater ciliate showing cilia distributed over the cell surface and around the mouth 64

The two largest groups of Rhizaria, foramniferans and radiolarians, are among the organisms referred to as amoebas. Amoebas move and feed by means of pseudopodia, temporary extensions of the cell. Foramniferans have porous shells called tests and are both freshwater and marine © 2012 Pearson Education, Inc. 65

Figure 16.14F A foraminiferan (inset SEM shows a foram test of calcium carbonate)
66

Figure 16.14G A radiolarian skeleton of silica
68

16.15 Can algae provide a renewable source of energy?
Fossil fuels are the organic remains of organisms that lived hundreds of millions of years ago and primarily consist of diatoms and primitive plants. © 2012 Pearson Education, Inc. 69

16.15 Can algae provide a renewable source of energy?
Lipid droplets in diatoms and other algae may serve as a renewable source of energy. If unicellular algae could be grown on a large scale, this oil could be harvested and processed into biodiesel. Numerous technical hurdles remain before industrial-scale production of biofuel from algae becomes a reality. © 2012 Pearson Education, Inc. 70

Figure 16.15 Green algae in a bioreactor
71

16.16 Some excavates have modified mitochondria
Excavata has recently been proposed as a group on the basis of molecular and morphological similarities. The name refers to an “excavated” feeding groove possessed by some members of the group. Excavates have modified mitochondria that lack functional electron transport chains and use anaerobic pathways such as glycolysis to extract energy. © 2012 Pearson Education, Inc. 72

Figure 16.12B A protist from a termite gut covered by thousands of flagella
Figure 16.12B A protist from a termite gut covered by thousands of flagella, viewed with scanning electron microscope (left) and light microscope (below). 74

Mixotrophy Euglena Figure 16.12A
Figure 16.12A Protist modes of nutrition: Euglena (part 3) Euglena 76

Autotrophy Heterotrophy Mixotrophy Caulerpa, a green alga
Figure 16.12A Autotrophy Heterotrophy Mixotrophy Figure 16.12A Protist modes of nutrition Caulerpa, a green alga Giardia, a parasite Euglena 78

Excavates include heterotrophic termite endosymbionts, autotrophic species, mixotrophs such as Euglena, the common waterborne parasite Giardia intestinalis, the parasite Trichomonas vaginalis, which causes 5 million new infections each year of human reproductive tracts, © 2012 Pearson Education, Inc. 79

Figure 16.16A A parasitic excavate: Trichomonas vaginalis
Flagella Figure 16.16A A parasitic excavate: Trichomonas vaginalis Undulating membrane 80

Excavates include heterotrophic termite endosymbionts, autotrophic species, mixotrophs such as Euglena, the common waterborne parasite Giardia intestinalis, the parasite Trichomonas vaginalis, which causes 5 million new infections each year of human reproductive tracts, and the parasite Trypanosoma, which causes sleeping sickness in humans. © 2012 Pearson Education, Inc. 81

Figure 16.16B A parasitic excavate: Trypanosoma (with blood cells)
82

16.17 Unikonts include protists that are closely related to fungi and animals
Unikonta is a controversial grouping joining Amoebozoans, which are protists and a group that includes animals and fungi. © 2012 Pearson Education, Inc. 83

Figure 16.17A An amoeba beginning to ingest an algal cell
85

Plasmodial slime molds are common where there is moist, decaying organic matter and consist of a single, multinucleate mass of cytoplasm undivided by plasma membranes, called a plasmodium. © 2012 Pearson Education, Inc. 86

Figure 16.17B A plasmodial slime mold: Physarum
87

Cellular slime molds are common on rotting logs and decaying organic matter and usually exist as solitary amoeboid cells, but when food is scarce, amoeboid cells swarm together, forming a slug-like aggregate that wanders around for a short time and then forms a stock supporting an asexual reproductive structure that produces spores. © 2012 Pearson Education, Inc. 88

Figure 16.17C An aggregate of amoeboid cells (left) and the reproductive structure of a cellular slime mold, Dictyostelium Figure 16.17C An aggregate of amoeboid cells (left) and the reproductive structure of a cellular slime mold, Dictyostelium 89

16.18 Archaeplastids include red algae, green algae, and land plants
Archaeplastids include: red algae, green algae, and land plants. © 2012 Pearson Education, Inc. 90

Figure 16.18A An encrusted red alga
92

Figure 16.18B Green algae, colonial (left) and unicellular (right)
Volvox Chlamydomonas 94

Ulva, or sea lettuce, is a multicellular green alga with a complex life cycle that includes an alternation of generations that consists of a multicellular diploid (2n) form, the sporophyte, that alternates with a multicellular haploid (1n) form, the gametophyte. © 2012 Pearson Education, Inc. 95

Mitosis Male gametophyte Spores Mitosis Gametes Female gametophyte Key
Figure 16.18C Mitosis Male gametophyte Spores Mitosis Gametes Female gametophyte Figure 16.18C The life cycle of Ulva, a multicellular green alga (step 1) Key Haploid (n) Diploid (2n) 96

Mitosis Male gametophyte Spores Mitosis Gametes Female gametophyte
Figure 16.18C Mitosis Male gametophyte Spores Mitosis Gametes Female gametophyte Fusion of gametes Figure 16.20C_s2 The life cycle of Ulva, a multicellular green alga (step 2) Zygote Key Haploid (n) Diploid (2n) 97

Mitosis Male gametophyte Spores Mitosis Gametes Female gametophyte
Figure 16.18C Mitosis Male gametophyte Spores Mitosis Gametes Female gametophyte Meiosis Fusion of gametes Figure 16.18C The life cycle of Ulva, a multicellular green alga (step 3) Sporophyte Zygote Mitosis Key Haploid (n) Diploid (2n) 98

16.19 EVOLUTION CONNECTION: Multicellularity evolved several times in eukaryotes
The origin of the eukaryotic cell led to an evolutionary radiation of new forms of life. Unicellular protists are much more diverse in form than simpler prokaryotes. Teaching Tips  The evolution of multicellularity typically results in the subdivision of labor in ways similar to modern human societies. Providing structure, acquiring and processing food, and facilitating movement are specialized functions of cells as well as members of society.  Figure presents one potential scenario to account for the diversity of eukaryotes. It is a very helpful organizer for the textbook and discussions of these groups.

Multicellular organisms (seaweeds, plants, animals, and most fungi) are fundamentally different from unicellular organisms. All of life’s activities occur within a single cell in unicellular organisms. A multicellular organism has various specialized cells that perform different functions and are interdependent. Teaching Tips  The evolution of multicellularity typically results in the subdivision of labor in ways similar to modern human societies. Providing structure, acquiring and processing food, and facilitating movement are specialized functions of cells as well as members of society.  Figure presents one potential scenario to account for the diversity of eukaryotes. It is a very helpful organizer for the textbook and discussions of these groups.

Multicellular organisms have evolved from three different lineages: SAR-stramenopiles, alveolata, rhizaria (brown algae), unikonts (fungi and animals), and archaeplastids (red algae, green algae, and plants). Teaching Tips  The evolution of multicellularity typically results in the subdivision of labor in ways similar to modern human societies. Providing structure, acquiring and processing food, and facilitating movement are specialized functions of cells as well as members of society.  Figure presents one potential scenario to account for the diversity of eukaryotes. It is a very helpful organizer for the textbook and discussions of these groups.

Both unicellular and multicellular All multicellular Animals
Figure 16.19a A hypothesis for the phylogeny of plants, fungi, and animals Red algae Archaeplastids Other green algae Green algae Charophytes Ancestral eukaryote Land plants Amoebozoans Nucleariid amoebas Unikonts Fungi Figure 16.19a A hypothesis for the phylogeny of plants, fungi, and animals Choanoflagellates Key All unicellular Both unicellular and multicellular All multicellular Animals

One hypothesis states that two separate unikont lineages led to fungi and animals, which diverged more than 1 billion years ago. A combination of morphological and molecular evidence suggests that choanoflagellates are the closest living protist relative of animals. Teaching Tips  The evolution of multicellularity typically results in the subdivision of labor in ways similar to modern human societies. Providing structure, acquiring and processing food, and facilitating movement are specialized functions of cells as well as members of society.  Figure presents one potential scenario to account for the diversity of eukaryotes. It is a very helpful organizer for the textbook and discussions of these groups.

A nucleariid (type of amoeba)
Figure 16.19b The closest living protist relatives of fungi (top) and animals (bottom) 16.19b-0 Nucleariids A nucleariid (type of amoeba) closest living protistan relative of fungi Fungi 1 billion years ago Individual choanoflagellate Choanoflagellates Colonial choanoflagellate Figure 16.19b-0 The closest living protist relatives of fungi (top) and animals (bottom) Sponge collar cell Animals Sponge

PROKARYOTES Chapter 16 Microbial Life: Prokaryotes and Protists 1

Similar presentations

Presentation on theme: "PROKARYOTES Chapter 16 Microbial Life: Prokaryotes and Protists 1"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

PROKARYOTES Chapter 16 Microbial Life: Prokaryotes and Protists 1

Similar presentations

Presentation on theme: "PROKARYOTES Chapter 16 Microbial Life: Prokaryotes and Protists 1"— Presentation transcript:

Similar presentations

About project

Feedback